test: use t.Context() instead of context.Background() (#1306)

The test context is cancelled when the test ends, so anything still holding it stops instead of leaking into the next test. Uses inside `t.Cleanup`, `defer` and `go func` blocks are left alone, as the context is already cancelled there.

Stacked on https://gitea.com/gitea/runner/pulls/1305.

Assisted-by: Codet
Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1306
Reviewed-by: bircni <[email protected]>

internal/pkg/report/joblog_test.go

@@ -43,7 +43,7 @@ func TestJobLog_MirrorsUploadedRows(t *testing.T) {
 	require.NoError(t, err)
 	cfg.Log.Job.Dir = t.TempDir()
 
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 	t.Cleanup(cancel)
 	task := &runnerv1.Task{Id: 41, Context: &structpb.Struct{}, Secrets: map[string]string{"TOKEN": "s3cret-value"}}
 	reporter := NewReporter(ctx, cancel, client, task, cfg)